I found a silver box as described by squirrel.
Chojin – maybe but seems odd to me
Gears – lived here eight years. Never been able to control them separately but until last week we had a very simple timer unit below the boiler, thermostat (basic twist dial in the hall).. The timer failed and was replaced with a more modern one with more functionality. Similarly, the thermostat was upgraded. It was explained to me that the thermostat would turn the CH on independently and the timer would control the water only. I am guessing that having seen the system, the engineer thinks the CH ‘should’ be capable of that.. It doesn’t which lead me to try and find out what is wrong. I am guessing that the fault has always been there..
By asking the question I am hoping to gain a bit of knowledge, no more that that.. I can at least make a suggestion as to what may be wrong to the plumber when he gets here. At least I now know that it possible that my system is designed like that and it may not be faulty. If that is the case, the new 60 thermostat in my hallway was not needed and serves no function, which the plumber should have known…
There is a thermostat on the hot water tank as well..
Thanks for replies